The field of art to which the invention pertains includes low lift platform transporter trucks, and more particularly devices adapted for tilting and for elevating a relatively small distance above the floor the load support of a pallet or platform type lift truck.
Various methods and devices for handling material on sheet-like or slip sheet pallets which may be drawn onto a load supporting surface of an industrial truck or tractor by gripping an edge portion of the pallet and pulling the load and slip sheet onto the supporting surface, and subsequently releasing the grip on the pallet edge and discharging it and the unit load from the supporting surface, have long been known in the art. The load supporting surface must be movable vertically and tiltable forwardly from a horizontal position in order to carry out the slip sheet pallet handling method.
Rider type counterweighted lift trucks having uprights mounted from the forward end have long been used for the handling of loaded slip sheet pallets by means of such push-pull type attachments. A representative push-pull attachment is manufactured by the assignee of this application under the trademark "Pul-Pac", Model B-5. To a limited degree low lift pedestrian or walkie-type transporter trucks have been used heretofore in combination with push-pull type attachments in applications where elevation of the load above a transport position or standard pallet height is not required. Major advantages result from the use of the much lower cost walkie-type truck as compared with a masted rider truck. One such known transporter type truck which is designed to jack-knife centrally thereof in order to tilt the load supporting surface so as to be capable of handling slip sheet palletized loads is Model MTP-WJ, manufactured by Otis Elevator Company of Cleveland, Ohio.
Also known is a prior low lift floor level pick-up truck in which hydraulic actuators are adapted to extend and retract longitudinally of the truck trail wheels which are mounted underneath fork tine members for the purpose of tilting the tines to a load pick-up position when retracted and raising the tines to load carrying position when extended. Such a device is disclosed in U.S. Pat. No. 3,495,730. It is not satisfactory partly because design criteria impose on the trail wheel a permissible design in a given truck design which is not capable of both tilting the fork tines to a floor load level pick-up position and raising the fork tines a distance which will enable them to clear wooden pallets and the like in a vertical direction for engagement, deposit and withdrawal of loads on the pallet.